cassia fistula

Cassia (legume)

Cassia is a genus of Fabaceae in the subfamilyCaesalpinioideae. Commonly called cassias, "cassia" is also the English name of Cinnamomum aromaticum in the Lauraceae (from which the spice cassiabark is derived), and some other species of Cinnamomum. In addition, the genus Cassia was for long ill-delimited with regards to the related Cassiinae - especially Senna -, many species of which were once placed herein. As a rule-of-thumb, Cassia sensu stricto contains the largest Cassiinae, usually mid-sized trees.

Ecology and uses

Owing to this confusion about which species actually belong into Cassia, many references to some sort of "cassia" are less than clear; usually it is hard or even impossible if a species of the present genus, of Senna, or of Cinnamomum is meant. "Cassia gum" for example is not made from Cassia in the present sense, but from Chinese Senna (sicklepod, Senna obtusifolia), formerly known as Cassia obtusifolia, C. toroides and several other taxa in the present genus.

"Cassia" is not infrequently encountered in texts on herbalism and alternative medicine. This is usually Senna however; while both genera contain plants with medical properties those of Senna seem to be more pronounced (or are simply better-studied). Still, Golden Shower Tree (C. fistula) is unequivocally identified and considered very potent in Ayurvedic medicine, where it is called aragvadha ("disease killer"). It contains elevated quantities of anthraquinones and consequently is mainly useful against gastrointestinal conditions (e.g. constipation or acid reflux) and to still bleeding. While its fruit pulp is considered a mild remedy, the roots are said to be so potent as to render their use dangerous if not supervised by a trained professional.

There exists some culinary use for cassia. The fruit pulp of some is eaten as a refreshing treat - similar to the related tamarind - , though it is important to note that not all species have edible fruit, and at least some have poisonous seed. Of course, as noted above, consuming too much of the pulp even in species in which it is edible is likely to result in fulminantpassing of stool. It is not quite clear to what extent Cassia leaves are used to brew herbal teas, as is common with those of Senna. And clearly, both Cassiinae pale by comparison to the effectively global importance of Cinnamomum aromaticum bark.

Systematics and taxonomy

There are hundreds of Cassiaspecies, but the exact number is still not clear. The reason is that Casiia was long used as a wastebin taxon for Cassieae in general, most notably Senna and Chamaecrista with which it makes up the Cassiinae. Those species are more recently moved to more correct placements, but the process is still ongoing due to the high number of species, with more than 1000 named taxa having been described for this genus altogether.